Until recently light emitting diode (LED) light sources were not in common use due to the lack of inexpensive LEDs having sufficient light output to serve as a substitute for incandescent, fluorescent and other conventional light sources. Further, the lack of blue and white LEDs limited the use of LEDs in conventional lighting applications.
Due to the wide availability of high output LEDs, as well as blue and white LEDs, LEDs are becoming increasingly popular for use as light sources in conventional lighting applications. LEDs have several advantages over incandescent and other conventional light sources, including increased energy efficiency, longer life, decreased heat generation, and other advantages.
However, a lighting fixture, such as for a pool or spa, comprising an array of LEDs acts quite differently from a conventional incandescent or halogen lamp. As a source, the LED array is much larger than the filament of a conventional lamp. Also, the light from a single LED emanates from an intense spot. The beams must be combined and shaped to allow for refraction when entering, and passage through, water on the way to illuminating the spa or pool walls and floor. The shaping must also avoid loss of light from the upper water surface in order to deliver sufficient illumination to the pool. The individual LED beams must conditioned by mixing in order to lower the spot light intensity delivered to the eye of an observer.
Conventional methods of controlling LED lights utilize pulse width modulated (PWM) control to vary the power, and thus the output intensity of the LEDs.